add support for loading FP constants +0.0 and +1.0 to the dag isel,
stop pretending -0.0 and -1.0 are machine constants


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24146 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/IA64/IA64ISelDAGToDAG.cpp b/lib/Target/IA64/IA64ISelDAGToDAG.cpp
index 1a83d89..d3487f2 100644
--- a/lib/Target/IA64/IA64ISelDAGToDAG.cpp
+++ b/lib/Target/IA64/IA64ISelDAGToDAG.cpp
@@ -321,6 +321,14 @@
 /* todo:
  * case ISD::DYNAMIC_STACKALLOC:
 */
+  case ISD::ConstantFP: {
+    if (cast<ConstantFPSDNode>(N)->isExactlyValue(+0.0))
+      return CurDAG->getRegister(IA64::F0, MVT::f64); // load 0.0
+    else if (cast<ConstantFPSDNode>(N)->isExactlyValue(+1.0))
+      return CurDAG->getRegister(IA64::F1, MVT::f64); // load 1.0
+    else
+      assert(0 && "Unexpected FP constant!");
+  }
 
   case ISD::FrameIndex: { // TODO: reduce creepyness
     int FI = cast<FrameIndexSDNode>(N)->getIndex();